U.S. patent application number 14/771127 was filed with the patent office on 2016-02-18 for nanostructured glasses and vitroceramics that are transparent in visible and infra-red ranges.
This patent application is currently assigned to CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE (CNRS). The applicant listed for this patent is CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE (CNRS). Invention is credited to Mathieu ALLIX, Thierry CARDINAL, Sebastien CHENU, Guy MATZEN, Emmanuel VERON.
Application Number | 20160046520 14/771127 |
Document ID | / |
Family ID | 48741319 |
Filed Date | 2016-02-18 |
United States Patent
Application |
20160046520 |
Kind Code |
A1 |
CHENU; Sebastien ; et
al. |
February 18, 2016 |
NANOSTRUCTURED GLASSES AND VITROCERAMICS THAT ARE TRANSPARENT IN
VISIBLE AND INFRA-RED RANGES
Abstract
The present invention relates to novel vitroceramic or lens
compositions that are nanostructured and transparent or
translucent, including at least 97%, such as 97% to 100%,
preferably 99% to 100%, by weight, relative to the total weight of
the material, of a composition having the following formula I:
(GeO.sub.2).sub.x(SiO.sub.2).sub.y(B.sub.2O.sub.3).sub.z(Ga.sub.2O.sub.3)-
.sub.a(Oxy.sub.1).sub.b(Oxy.sub.2).sub.k (I) where Oxy.sub.1 is an
oxide selected from ZnO, MgO, NbO.sub.2.5, WO.sub.3, NiO, SnO,
TiO.sub.2, BiO.sub.1.5, AgO, CaO, MnO, or a mixture thereof,
selected preferably from ZnO, MgO, NbO.sub.2.5, WO.sub.3, NiO, SnO,
AgO, CaO, MnO, or a mixture thereof, selected more preferably from
ZnO, MgO, AgO, BiO.sub.1.5, NbO.sub.2.5, Or a mixture thereof,
selected most preferably from ZnO, MgO, AgO, NbO.sub.2.5, or a
mixture thereof, and Oxy.sub.2 is an oxide selected from Na.sub.2O,
K.sub.2O or a mixture thereof, Oxy.sub.2 is preferably Na.sub.2O,
and x, y, z, a, b and k are as defined in claim 1, to the
manufacturing method thereof and to the uses thereof in the field
of optics.
Inventors: |
CHENU; Sebastien; (Olivet,
FR) ; ALLIX; Mathieu; (Olivet, FR) ; MATZEN;
Guy; (Saint Denis En Val, FR) ; VERON; Emmanuel;
(Saint Jean Le Blanc, FR) ; CARDINAL; Thierry;
(Salles, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE (CNRS) |
Paris |
|
FR |
|
|
Assignee: |
CENTRE NATIONAL DE LA RECHERCHE
SCIENTIFIQUE (CNRS)
Paris
FR
|
Family ID: |
48741319 |
Appl. No.: |
14/771127 |
Filed: |
February 28, 2014 |
PCT Filed: |
February 28, 2014 |
PCT NO: |
PCT/EP2014/053932 |
371 Date: |
August 27, 2015 |
Current U.S.
Class: |
501/32 ; 501/42;
501/63; 501/72; 501/73; 501/79; 65/33.9 |
Current CPC
Class: |
C03C 10/00 20130101;
C03B 32/02 20130101; C03C 3/097 20130101; C03C 3/078 20130101; C03C
3/062 20130101; C03C 10/0009 20130101; C03C 3/066 20130101; C03C
3/089 20130101; C03C 3/064 20130101; C03C 3/253 20130101; C03C 4/10
20130101 |
International
Class: |
C03C 10/00 20060101
C03C010/00; C03C 3/078 20060101 C03C003/078; C03B 32/02 20060101
C03B032/02; C03C 3/062 20060101 C03C003/062; C03C 3/066 20060101
C03C003/066; C03C 3/253 20060101 C03C003/253; C03C 3/097 20060101
C03C003/097 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2013 |
FR |
1351795 |
Claims
1-60. (canceled)
61. A nanostructured vitroceramic, either transparent or
translucent, with essentially zero Li.sub.2O content, containing
97% to 100% by weight in relation to the overall weight of the
material, of a composition of the following formula I:
(GeO.sub.2).sub.x(SiO.sub.2).sub.y(B.sub.2O.sub.3).sub.z(Ga.sub.2O.sub.3)-
.sub.a(Oxy.sub.1).sub.b(Oxy.sub.2).sub.k (I) where Oxy.sub.1 is an
oxide selected from among ZnO, MgO, NbO.sub.2.5, WO.sub.3, NiO,
SnO, TiO.sub.2, BiO.sub.1.5, AgO, CaO, MnO, or a mixture thereof,
and Oxy.sub.2 is an oxide selected from Na.sub.2O, K.sub.2O, or a
mixture thereof, and x is within the range between 0 and 98, and y
is within the range between 0 and 60, and x and y are not
simultaneously zero, and z is within the range between 0 and 20, x,
y, z are such that x+y+z lie within the range between 40 and 98, a
is within the range between 0.1 and 50, b is within the range
between 0 and 35, and k is within the range between 0 and 7, and x,
y, z, a, b and k are such that x+y+z+a+b+k=100.
62. Nanostructured glass, either transparent or translucent,
containing 97% to 100% by weight in relation to the overall weight
of the material, of a composition of the following formula I:
(GeO.sub.2).sub.x(SiO.sub.2).sub.y(B.sub.2O.sub.3).sub.z(Ga.sub.2O.sub.3)-
.sub.aOxy.sub.1).sub.b(Oxy.sub.2).sub.k (I) where Oxy.sub.1 is an
oxide selected from among ZnO, MgO, NbO.sub.2.5, WO.sub.3, NiO,
SnO, TiO.sub.2, BiO.sub.1.5, AgO, CaO, MnO, or a mixture thereof,
and Oxy.sub.2 is an oxide selected from among Na.sub.2O, K.sub.2O
or a mixture thereof, and x is within the range between 0 and 98,
and y is within the range between 0 and 60, and x and y are not
simultaneously zero, and z is within the range between 0 and 20, x,
y, z are such that x+y+z lie within the range between 40 and 98, a
is within the range between 0.1 and 50, b is within the range
between 0 and 35, and k is within the range between 0 and 7, and x,
y, z, a, b and k are such that x+y+z+a+b+k=100.
63. Vitroceramic according to claim 61, wherein x and y are such
that x+y.gtoreq.40, in particular x+y.gtoreq.50.
64. Vitroceramic according to claim 61, wherein x is equal to 0 and
y is within the range between 40 and 60, more preferably between 43
and 55.
65. Vitroceramic according to claim 61, wherein y is equal to 0 and
x is within the range 50 and 98 and z is equal to 0.
66. Vitroceramic or glass according to claim 61, wherein x and y
are each independently included within the range between 10 and 80,
in the case of x; and 10 and 60, in the case of y, and x and y are
such that x+y lie within the range between 50 and 95, more
preferably between 60 and 98, and most preferably between 80 and
95.
67. Vitroceramic according to claim 61, containing dopants in
addition to the composition formula (I) in order to attain 100% per
unit mass.
68. Manufacturing process of a nanostructured glass according to
claim 62, comprising the successive steps of: 1--melting of initial
oxides, or if applicable precursors thereof, present in powder
form, at a temperature within the range between 900.degree. C. and
1700.degree. C.; 2--cooling, producing a transparent or translucent
nanostructured glass containing 97% to 100% by weight, in relation
to the overall weight of the glass, of a composition of the
following formula I:
(GeO.sub.2).sub.x(SiO.sub.2).sub.y(B.sub.2O.sub.3).sub.z(Ga.sub.2O.sub.3)-
.sub.aOxy.sub.1).sub.b(Oxy.sub.2).sub.k (I) where Oxy.sub.1 is an
oxide selected from among ZnO, MgO, NbO.sub.2.5, WO.sub.3, NiO,
SnO, TiO.sub.2, BiO.sub.1.5, AgO, CaO, MnO, or a mixture thereof,
and Oxy.sub.2 is an oxide selected from among Na.sub.2O, K.sub.2O
or a mixture thereof, and x is within the range between 0 and 98,
and y is within the range between 0 and 60, and x and y are not
simultaneously zero, and z is within the range between 0 and 20
x+y+z lies within the range between 40 and 98, a is within the
range between 0.1 and 50, b is within the range between 0 and 35,
and k is within the range between 0 and 7, and x, y, z, a, b and k
are such that x+y+z+a+b+k=100.
69. Manufacturing process of a nanostructured vitroceramic
according to claim 61, comprising the successive steps of:
1--manufacture of a transparent or translucent nanostructured glass
with essentially zero Li.sub.2O content and containing 97% to 100%
by weight in relation to the overall weight of the material, of a
composition of the following formula I:
(GeO.sub.2).sub.x(SiO.sub.2).sub.y(B.sub.2O.sub.3).sub.z(Ga.sub.2O.su-
b.3).sub.aOxy.sub.1).sub.b(Oxy.sub.2).sub.k (I) where Oxy.sub.1 is
an oxide selected from among ZnO, MgO, NbO.sub.2.5, WO.sub.3, NiO,
SnO, TiO.sub.2, BiO.sub.1.5, AgO, CaO, MnO, or a mixture thereof,
and Oxy.sub.2 is an oxide selected from Na.sub.2O, K.sub.2O or a
mixture thereof, and x is within the range between 0 and 98, and y
is within the range between 0 and 60, and x and y are not
simultaneously zero, and z is within the range between 0 and 20, x,
y, z are such that x+y+z lies within the range between 40 and 98, a
is within the range between 0.1 and 50, b is within the range
between 0 and 35, and k is within the range between 0 and 7, and x,
y, z, a, b and k are such that x+y+z+a+b+k=100, according to a
process comprising the successive steps of: melting of the initial
oxides, or if applicable their precursors, present in powder form,
at a temperature within the range between 900.degree. C. and
1700.degree. C., and then cooling; 2--thermal crystallisation
treatment of the glass at a temperature within the range between
400.degree. C. and 900.degree. C., for a period within the range
between 15 minutes and 48 hours.
70. Use of a glass according to claim 62, for the manufacture of
optical material, including masses, powders, fibres or layers; for
the manufacture of material for medical imaging, for lighting or
for displays; for laser marking.
71. The nanostructured vitroceramic of claim 61, containing 99% to
100% by weight in relation to the overall weight of the material,
of a composition of the formula I.
72. The nanostructured vitroceramic of claim 61, wherein Oxy.sub.1
is an oxide selected from ZnO, MgO, AgO, BiO.sub.1.5, NbO.sub.2.5,
or a mixture thereof.
73. The nanostructured vitroceramic of claim 61, wherein Oxy.sub.2
is Na.sub.2O.
74. The nanostructured vitroceramic of claim 61, wherein z is
within the range between 0 and 10.
75. The nanostructured vitroceramic of claim 61, wherein a is
within the range between 0.5 and 25.
76. The nanostructured vitroceramic of claim 61, wherein b is
within the range between 1 and 25.
77. The nanostructured vitroceramic of claim 61, wherein k is
within the range between 0 and 5.
78. A nanostructured vitroceramic, either transparent or
translucent, with essentially zero Li.sub.2O content, containing
99% to 100% by weight in relation to the overall weight of the
material, of a composition of the following formula I:
(GeO.sub.2).sub.x(SiO.sub.2).sub.y(B.sub.2O.sub.3).sub.z(Ga.sub.2O.sub.3)-
.sub.aOxy.sub.1)b(Oxy.sub.2).sub.k (I) where Oxy.sub.1 is an oxide
selected from ZnO, MgO, AgO, BiO.sub.1.5, NbO.sub.2.5, or a mixture
thereof, and Oxy.sub.2 is Na.sub.2O, and x is within the range
between 0 and 98, and y is within the range between 0 and 60, and x
and y are not simultaneously zero, and z is within the range
between 0 and 10, x, y, z are such that x+y+z lie within the range
between 40 and 98, a is within the range between 0.5 and 25, b is
within the range between 1 and 25, and k is within the range 0 and
5, and x, y, z, a, b and k are such that x+y+z+a+b+k=100.
79. The nanostructured glass of claim 62, containing 99% to 100% by
weight in relation to the overall weight of the material, of a
composition of the formula I.
80. The nanostructured glass of claim 62, wherein Oxy.sub.1 is an
oxide selected from ZnO, MgO, AgO, BiO.sub.1.5, NbO.sub.2.5, or a
mixture thereof.
81. The nanostructured glass of claim 62, wherein Oxy.sub.2 is
Na.sub.2O.
82. The nanostructured glass of claim 62, wherein z is within the
range between 0 and 10.
83. The nanostructured glass of claim 62, wherein a is within the
range between 0.5 and 25.
84. The nanostructured glass of claim 62, wherein b is within the
range between 1 and 25.
85. The nanostructured glass of claim 62, wherein k is within the
range 0 and 5.
86. Nanostructured glass, either transparent or translucent,
containing 99% to 100% by weight in relation to the overall weight
of the material, of a composition of the following formula I:
(GeO.sub.2).sub.x(SiO.sub.2).sub.y(B.sub.2O.sub.3).sub.z(Ga.sub.2O.sub.3)-
.sub.aOxy.sub.1).sub.b(Oxy.sub.2).sub.k (I) where Oxy.sub.1 is an
oxide selected preferably from ZnO, MgO, AgO, BiO.sub.1.5,
NbO.sub.2.5, or a mixture thereof, and Oxy.sub.2 is Na.sub.2O, and
x is within the range between 0 and 98, and y is within the range
between 0 and 60, and x and y are not simultaneously zero, and z is
within the range between 0 and 10, x, y, z are such that x+y+z lie
within the range between 40 and 98, a is within the range between
0.5 and 25, b is within the range between 1 and 25, and k is within
the range between 0 and 5, and x, y, z, a, b and k are such that
x+y+z+a+b+k=100.
87. Manufacturing process of a nanostructured glass according to
claim 86, comprising the successive steps of: 1--melting of initial
oxides, or if applicable precursors thereof, present in powder
form, at a temperature within the range between 900.degree. C. and
1700.degree. C.; 2--cooling, producing a transparent or translucent
nanostructured glass containing 99% to 100% by weight, in relation
to the overall weight of the glass, of a composition of the
following formula I:
(GeO.sub.2).sub.x(SiO.sub.2).sub.y(B.sub.2O.sub.3).sub.z(Ga.sub.2O.sub.3)-
.sub.a(Oxy.sub.1).sub.b(Oxy.sub.2).sub.k (I) where Oxy.sub.1 is an
oxide selected from among ZnO, MgO, AgO, BiO.sub.1.5, NbO.sub.2.5,
or a mixture thereof, and Oxy.sub.2 is Na.sub.2O, and x is within
the range between 0 and 98, and y is within the range between 0 and
60, and x and y are not simultaneously zero, and z is within the
range between 0 and 10, x+y+z lies within the range between 40 and
98, a is within the range between 0.5 and 25, b is within the range
between 1 and 25, and k is within the range between 0 and 5, and x,
y, z, a, b and k are such that x+y+z+a+b+k=100.
88. The process according to claim 69, wherein the thermal
crystallisation treatment is performed at a temperature within the
range 600.degree. C. and 800.degree. C., for a period within the
range between 15 minutes and 6 hours.
89. Manufacturing process of a nanostructured vitroceramic
according to claim 61, comprising the successive steps of:
1--manufacture of a transparent or translucent nanostructured glass
with essentially zero Li.sub.2O content and containing 99% to 100%
by weight in relation to the overall weight of the material, of a
composition of the following formula I:
(GeO.sub.2).sub.x(SiO.sub.2).sub.y(B.sub.2O.sub.3).sub.z(Ga.sub.2O.su-
b.3).sub.aOxy.sub.1).sub.b(Oxy.sub.2).sub.k (I) where Oxy.sub.1 is
an oxide selected from among ZnO, MgO, AgO, BiO.sub.1.5,
NbO.sub.2.5, or a mixture thereof, and Oxy.sub.2 is Na.sub.2O, and
x is within the range between 0 and 98, and y is within the range
between 0 and 60, and x and y are not simultaneously zero, and z is
within the range between 0 and 10, x, y, z are such that x+y+z lies
within the range between 40 and 98, a is within the range between
0.5 and 25, b is within the range between 1 and 25, and k is within
the range between 0 and 5, and x, y, z, a, b and k are such that
x+y+z+a+b+k=100, according to a process comprising the successive
steps of: melting of the initial oxides, or if applicable their
precursors, present in powder form, at a temperature within the
range between 900.degree. C. and 1700.degree. C., and then cooling;
2--thermal crystallisation treatment of the glass at a temperature
within the range between 600.degree. C. and 800.degree. C., for a
period within the range between 15 minutes and 6 hours, and
preferably between 30 minutes and 2 hours.
90. Glass according to claim 62, wherein x and y are such that
x+y.gtoreq.40, in particular x+y.gtoreq.50.
91. Glass according to claim 62, wherein x is equal to 0 and y is
within the range between 40 and 60, more preferably between 43 and
55.
92. Glass according to claim 62, wherein y is equal to 0 and x is
within the range 50 and 98 and z is equal to 0.
93. Vitroceramic or glass according to claim 62, wherein x and y
are each independently included within the range between 10 and 80,
in the case of x; and 10 and 60, in the case of y, and x and y are
such that x+y lie within the range between 50 and 95, more
preferably between 60 and 98, and most preferably between 80 and
95.
94. Glass according to claim 62, containing dopants in addition to
the composition formula (I) in order to attain 100% per unit
mass.
95. Use of a vitroceramic according to claim 61, for the
manufacture of optical material, including masses, powders, fibres
or layers; for the manufacture of material for medical imaging, for
lighting or for displays; for laser marking.
Description
[0001] This invention relates to novel vitroceramic or glass
compositions that are nanostructured, transparent or translucent,
their methods of manufacture, and their uses.
[0002] Optical applications require the use of vitroceramics or
glasses that transparent, or at very least translucent. The
wavelengths of interest are those of the visible light spectrum,
i.e. within the range between 400 nm and 800 nm, and within the
infra-red range between 800 nm and 8000 nm.
[0003] Compositions of transparent or translucent nanostructured
materials have previously been described. However, these refer
essentially to polycrystalline ceramics produced from nanometric
and vitroceramic precursors.
[0004] The methods of manufacture for polycrystalline ceramics
generally apply precursors in the form of nanometric particles,
which are relatively expensive owing to their complex synthesis, as
is shown in the work of Krell et al. (Transparent compact ceramics:
Inherent physical issues. Optical materials 2009, 31 (8),
1144-1150). The particles undergo a stage of pressing, followed by
a stage of sintering (fritting), at a temperature often greater
than 1500.degree. C., and typically at high pressure. The growth of
crystals takes place during this sintering stage. Moreover, it
should be noted that the precursors of such ceramics present a real
health hazard.
[0005] Such transparent polycrystalline ceramics, produced from
nanometric precursors, are extremely well suited for
high-performance applications in optics, but entail inordinately
high production costs for the most common applications, for example
displays, lighting or medical imaging procedures.
[0006] There is therefore a need for new transparent or translucent
glasses and vitroceramics, in both the visible and infra-red ranges
up to 8 .mu.m (wavelength within the range between 400 nm and 8
.mu.m), which will combine the ability to adjust their optical
properties with a relatively inexpensive procedure of manufacture,
for example of the glass-making type.
[0007] Transparent or translucent vitroceramics that are based on
germanates and/or silicates, obtained using a glass-making
procedure, but which contain fluorine (fluorides and oxyfluorides)
or chalcogens (including sulphides), have previously been described
in the literature, for example in papers by De Pablos-Martin et al
(2012), International Materials Reviews 57(3): 165-186, and Zhang
et al, Journal of Non-Crystalline Solids, 2004, 337, 130-135. These
show high transparency in both the visible and the infra-red, but
have low chemical stability. Moreover, fluorine, which is extremely
volatile at high temperatures, is highly corrosive and toxic, thus
requiring the use of expensive secure industrial plant.
[0008] Transparent or translucent vitroceramics based on germanates
and/or silicates, obtained using a glass-making procedure, but
which contain barium oxide (BaO; see US 2005/0159289), aluminates
(Al.sub.2O.sub.3; see US 2003/00133593 and WO 01/28943), lithium
oxide (Sigaev et al, Nanotechnology 23 (2012) 01708 7 pp) or have a
high sodium oxide content (molar level greater than 8% in
Na.sub.2O; see Zhou et al, Adv. Funct. Mater. 2009, 19, 2081-2088)
have also been described.
[0009] Bayya et al (U.S. Pat. No. 5,786,287) have reported
vitroceramics that are high in Y.sub.2O.sub.3, La.sub.2O.sub.3 or
Gd.sub.2O.sub.3. Thus, in these vitroceramics, Y.sub.2O.sub.3,
La.sub.2O.sub.3 or Gd.sub.2O.sub.3 cannot be construed as simple
dopants. It should be specially noted that vitroceramics produced
according to Bayya et al are transparent only in the infra-red
range (wavelength in the range between 2 .mu.m and 5 .mu.m), but
not in the visible, and show very high crystallisation rates
(greater than 80% by volume). Moreover, the glasses described do
not display nanostructuring.
[0010] Furthermore, Duan et al (Applied Physics Letters 2006, 89,
183119, also Journal of Non-Crystalline Solids 2008, 354,
4695-4697) and Yu et al (Journal of Physics and Chemistry of Solids
2010, 71, 1656-1659, also Physica B 2011, 406, 3101-3103) describe
nanocrystalline vitroceramics that are high in SiO.sub.2. Such
vitroceramics are obtained through thermal treatment from a solid
obtained using the sol-gel method, therefore such vitroceramics are
not obtained by means of a glass-making procedure, since the
intermediate solid is not a glass, but rather a desiccated gel.
Moreover, such vitroceramic compositions contain 89% and 90% molar
SiO.sub.2. Materials developed using Duan et al's and Yu et al's
procedure correspond to only a restricted range of vitroceramics,
and hence also of optical properties. We might also mention
vitroceramics that are high in SiO.sub.2 (i.e. content greater than
60%) by Lipinska-Kalita et al (J. Non-Crystalline Solids 352 (2006)
524-527).
[0011] Murthy et al (Physics and Chemistry of Glasses, Vol. 8, no.
1, February 1967) report ternary glasses with the formula
M.sub.2O--Ga.sub.2O.sub.3--GeO.sub.2, in which M. is an alkaline
metal, selected from Li, Na or K. In this paper, the authors
conducted a study intended to define ranges of vitrifiable
composition. Outside those ranges the ternary mixture will
crystallise at least in part, thereby resulting in the appearance
of crystals here and there. However, we should note that the size
of the crystals was not reported, other than the concentration of
weight in the vitreous matrix.
[0012] International application WO2008/075546 dealt with glasses
for sensors, where these glasses had transmittance levels of at
least 50% at a wavelength of 5.5 .mu.m, and no greater than 10% at
a wavelength of 7.0 .mu.m. Glasses produced according to
WO2008/075546 therefore act as filters at certain wavelengths.
Glasses produced according to WO2008/075546 include, in moles: from
10% to 50% Bi.sub.2O.sub.3; from 20% to 85% GeO.sub.2; from 0% to
19% Ga.sub.2O.sub.3; and 0% to 15% Al.sub.2O.sub.3.
[0013] Chinese patent application CN1587142 was concerned with
glasses of the germanate type, doped with bismuth of a molar
composition including: 90% to 99.98% GeO.sub.2; 0.01% to 5 mol %
Bi.sub.2O.sub.3; and 0.01% to 9 mol % M, with M being selected from
among Al.sub.2O.sub.3, Ta.sub.2O.sub.5, Ga.sub.2O.sub.3 and
B.sub.2O.sub.3. Glasses obtained according to CN1587142 are
coloured (from fleshy-pink to violet-red or brownish-red) owing to
their high Bi.sub.2O.sub.3 content. They are also fluorescent.
[0014] However, neither the paper by Murthy et al, nor the
WO2008/077546 or CN1587142 applications reports nanostructured
glasses comparable to the glasses of this invention, in which we
obtain nanostructuring by segregating out galates (phases that are
rich in gallium). Moreover, as already emphasised, those papers are
in any case not concerned with vitroceramics. In particular, Murthy
et al do not report any vitroceramic since the glass containing
crystals has not undergone subsequent thermal treatment, which
would indeed facilitate enhancement of the material's physical and
thermal properties. Moreover, Murthy et al do not report a
nanostructured vitroceramic.
[0015] In contrast to the materials of the prior art, this
applicant discovered, much to their own surprise, new
nanostructured and transparent (or at least translucent) glasses
and vitroceramics based on gallium and silica and/or germanate.
[0016] Vitroceramics, as well as the glasses of this invention, are
nanostructured. Nanostructuring of vitroceramics corresponds to the
presence of crystals of nanometric sizes in the vitreous
matrix.
[0017] Nanostructuring of glasses comes about from a segregation or
separation of phase. Thus, images of electronic microscopies in
transmission reveal the appearance of domains of nanometric size
(phase 1), which are included in a matrix (phase 2). Depending on
the composition of the glass, phase separation is of the
nucleation-growth or spinel type. In the case of a
nucleation-growth phase, the nanodomains have a spherical shape,
whereas in the case of a separation of the spinel type, the
nanodomains are intertwined within the matrix.
[0018] Domains of nanometric size (vitreous in the case of
nanostructured glasses, or equivalent to nanocrystals in the case
of vitroceramics) are homogenous in both composition and size, and
their distribution is uniform within the vitreous matrix.
[0019] The size, shape and proportions of nanostructured domains of
glasses and nanometric crystals of vitroceramics can be controlled
through the nominal composition, also to a lesser extent by the
glass-making procedure.
[0020] These domains of nanometric size are obtained through the
segregation of a phase that is high in gallium, this element being
then concentrated in these nanometric domains. On the other hand,
the residual concentration of gallium in the vitreous matrix is
very low. It is by controlling the segregation of galates that we
maintain control over nanostucturation (i.e. the dimensions and
shapes of nanodomains) of glasses and vitroceramics, and hence also
their transparency.
[0021] Moreover, vitroceramics can readily be obtained under this
invention by means of an inexpensive glass-making procedure.
[0022] In contrast to prior art, it should also be noted that,
under this invention, glasses and vitroceramics show no detectable
content of BaO, aluminate (Al.sub.2O.sub.3), or of lithium oxide
(Li.sub.2O), and a molar content less than or equal to 7% in
Na.sub.2O. Moreover, compositions under this invention contain
neither fluorides nor chalcogens. In addition, under this
invention, they may contain dopants, in particular of rare earth
and transition elements with a molar content less than 3% of the
composition, preferably less than 1%. The introduction of those
elements in excessive amounts will indeed result in the loss of the
transparency properties of vitroceramics according to the
invention.
[0023] For the purposes of this invention, the term "glass" means
an amorphous inorganic solid that displays the phenomenon of
vitreous transition. A glass is obtained by cooling from a liquid
phase. Thus, it is not obtained in powder form. Hence, glass under
this invention is not obtained using a sol-gel procedure.
[0024] For the purposes of this invention, by the term
"vitroceramic" we mean an inorganic material comprising a vitreous
matrix (i.e. an amorphous phase) and crystals, preferably of
nanometric size, with a controllable crystallisation level within
the range 2% to 75%. In other words, between 2% and 75% of the
material is crystalline by volume. The vitroceramic's
crystallisation rate should preferably be between 10% and 60%.
Thus, the crystals are encased within the matrix of glass. This
material is not obtained in powder form.
[0025] For the purposes of this invention, by the term "nanometric
size" we mean a size within the range of 1 nm and 500 nm, and
preferably between 5 nm and 150 nm.
[0026] For the purposes of this invention, by the term
"transparent" we mean one can see through the material. Where
applicable, this qualitative notion of transparency is specified in
quantitative terms using a measure of specular light transmission.
The protocol for measuring specular light transmission entails
measuring the intensity of light according to the incident rays of
light. A material may be considered as being transparent (in
particular for optical applications) for a given wavelength when
its specular light transmission is greater than or equal to
30%.
[0027] For the purposes of this invention, by the term
"translucent" we mean that light will pass through the material,
but it is not possible to see through the material distinctly.
Where applicable, this notion of translucence is specified by a
measure of total light transmission. The protocol for measuring
total transmission entails measuring the intensity of light (i.e.
specular and diffused) according to a solid 180.degree. angle at a
given wavelength.
[0028] It is understood that, in this context, the notions of
transparency and translucency extend to the thickness of the
material. Typically, the samples from which measurements are taken
will have a thickness within a range between 1 nm and 10 nm.
[0029] In this description, the terms "material" or "materials"
refer to the transparent or translucent nanostructured glasses and
vitroceramics of this invention.
[0030] For the purposes of this invention, "segregation" means that
a homogenous phase is broken down into differing composition
domains. There are two types of segregation, namely: --Segregation
of the "nucleation-growth"type, which produces spherical domains
within the matrix, as shown for example in FIG. 2. [0031]
Segregation of the "spinel" type, which produces intertwined
domains, as shown for example in FIG. 3.
[0032] Materials under this invention are "nanostructured", meaning
they present a texture on a nanometric scale.
[0033] For the purposes of this invention, "nanostructuring" means
that glasses and vitroceramics comprise composition domains of
nanometric sizes, typically obtained through segregation. Those
domains are characterised by having a distinct composition. In the
case of glasses, the nanodomains (domains of nanometric sizes) are
vitreous. In the case of vitroceramics, nanodomains correspond to
crystals of nanometric size.
[0034] For the purposes of this invention, "glass-making process"
means a procedure enabling one to obtain a glass or vitroceramic
from raw materials in the form of powders, thus powders being not
nanometric precursors. A procedure of this type comprises a step of
melting of raw materials in the form of powders, producing a
high-temperature liquid, followed by a step of cooling that liquid,
producing the glass. A glass-making vitroceramic manufacturing
process also comprises a step of thermal crystallisation
treatment.
[0035] For the purposes of this invention, "thermal crystallisation
treatment" means heating of the glass, allowing the controlled
crystallisation thereof.
[0036] For the purposes of this invention, "composition that shows
an essentially zero content for a constituent" means that the
composition contains, for example, less than 0.1% by weight, and
preferably less than 0.01% by weight of that constituent, in
relation to the overall weight of that composition. Specifically, a
composition that presents essentially zero content of a given
constituent may still include trace amounts of that constituent,
but should preferably not contain it at all.
[0037] In the description of this invention, variables a, b, k, x,
y and z (referring to the standard composition of formula 1) refer
to molar proportions. Throughout this document, moreover, unless
otherwise indicated percentages are per-unit-mass percentages, and
are expressed in relation to the total weight of the element in
question. For example, when it is stated that a composition or
mixture contains 3% of a given compound, it is understood that this
composition or mixture contains 3% by weight of that compound in
relation to the overall weight of that composition or mixture.
Moreover, it is understood that when in this invention it is stated
that one of the variables falls within the range of two values, the
limits indicated are included within that range of values. Thus,
when we say "z falls within the range 0 to 10", it is understood
that z is between 0 and 10, including both 0 and 10.
[0038] One purpose of this invention therefore concerns transparent
or translucent nanostructured glasses based on silica and/or
germanium oxides, and gallium oxide.
[0039] A further purpose of this invention concerns transparent or
translucent nanostructured vitroceramics based on silica and/or
germanium oxides, and gallium oxide.
[0040] A further purpose of this invention concerns a process for
the manufacture of transparent or translucent nanostructured
glasses based on silica and/or germanium oxides, and gallium oxide,
comprising a step of separation (segregation).
[0041] A further purpose of this invention concerns a manufacturing
process of transparent or translucent nanostructured vitroceramics
based on silica and/or germanium oxides, and gallium oxide,
comprising a step of thermal crystallisation treatment of a glass
with the corresponding composition.
[0042] A further purpose of this invention concerns the use of
transparent or translucent nanostructured vitroceramics based on
silica and/or germanium oxides, and gallium oxide, for the
manufacture of optical materials, and specifically of the
luminescent type (i.e. fluorescent, phosphorescent).
[0043] A further purpose of this invention concerns the use of
transparent or translucent nanostructured glasses based on silica
and/or germanium oxides, and gallium oxide, for the manufacture of
lighting or display material.
Glasses and Vitroceramics
[0044] The vitroceramic or glass according to this invention, which
is nanostructured and transparent or translucent, contains at least
97%, i.e. from 97% to 100%, and preferably from 99% to 100% by
weight, in relation to the overall weight of the material, of a
composition of the following formula I:
(GeO.sub.2).sub.x(SiO.sub.2).sub.y(B.sub.2O.sub.3).sub.z(Ga.sub.2O.sub.3-
).sub.a(Oxy.sub.1).sub.b(Oxy.sub.2).sub.k (I)
[0045] where
[0046] Oxy.sub.1 is an oxide selected from ZnO, MgO, NbO.sub.2.5,
WO.sub.3, NiO, SnO, TiO.sub.2, BiO.sub.1.5, AgO, CaO, MnO or a
mixture thereof, selected preferably from ZnO, MgO, NbO.sub.2.5,
WO.sub.3, NiO, SnO, AgO, CaO, MnO, or a mixture thereof, selected
more preferably from ZnO, MgO, AgO, BiO.sub.1.5, or a mixture
thereof, selected most preferably from ZnO, MgO, AgO, or a mixture
thereof, and
[0047] Oxy.sub.2 represents an oxide selected from Na.sub.2O,
K.sub.2O or a mixture thereof, Oxy.sub.2 is preferably Na.sub.2O,
and
[0048] x is within the range between 0 and 98, and
[0049] y is within the range between 0 and 60, and
[0050] x and y are not simultaneously zero, and
[0051] z is within the range between 0 and 20, preferably between 0
and 10,
[0052] x+y+z is within the range between 40 and 98,
[0053] a is within the range between 0.1 and 50, preferably between
0.5 and 25,
[0054] b is within the range between 0 and 35, preferably between 1
and 35, and
[0055] k is within the range between 0 and 7, preferably between 0
and 5, and
[0056] x, y, z, a, b and k are such that x+y+z+a+b+k=100.
[0057] In formula (I) above, the oxides of germanium, silicon and
boron are glass-forming oxides.
[0058] The vitroceramic or glass according to the invention should
preferably be characterised in that x and y are such that
x+y.gtoreq.40, and preferably x+y.gtoreq.50.
[0059] In one particular embodiment, z is equal to 0.
[0060] As previously mentioned, both vitroceramics and glasses
under this invention are nanostructured. The nanostructuring of
vitroceramics corresponds to the presence of crystals of nanometric
size within the vitreous matrix. Nanostructuring of glasses
corresponds to a segregation (separation) of phase. In the
materials under this invention, nanometric size domains (in the
case of glasses), or nanocrystals (in the case of vitroceramics)
are homogenous in both composition and size, and their distribution
is uniform within the vitreous matrix.
[0061] The shape and size of nanodomains or nanocrystals is
adjustable depending on the nominal composition, and to a lesser
extent on the manufacturing process of glasses. It is the
nanometric size of that structure that imparts transparency to both
glasses and vitroceramics under this invention.
[0062] Without wishing to be impeded by theory, it would appear
that these nanodomains are obtained through the segregation of a
phase high in gallium, since this element is concentrated in those
nanometric domains. On the other hand, the residual concentration
of gallium in the vitreous matrix is very low. Gallium is
associated with another oxide (Oxy.sub.1) during its segregation,
thereby forming a phase that is high in gallium and Oxy.sub.1,
which might well be noted (Ga.sub.2O.sub.3) (Oxy.sub.1). In glasses
that contain zinc oxide, for example, we can segregate a vitreous
phase of zinc galate (Ga.sub.2O.sub.3) (ZnO), which will then
crystallise when developing a vitroceramic made of nanocrystals of
ZnGa.sub.2O.sub.4.
[0063] Thus, both gallium oxide and Oxy.sub.1 form essential
constituents of the "galate" nanodomain or phase of materials under
this invention.
[0064] Advantageously, a is within the range between 1 and 50,
preferably between 1 and 25.
[0065] Advantageously, b is within the range between 1 and 25,
preferably between 2 and 25.
[0066] In any specific embodiment, a lies within the range between
1 and 50 (preferably between 1 and 25), while b lies within the
range between 1 and 35, more preferably between 1 and 25, and most
preferably between 2 and 25.
[0067] In the materials according to this invention, the presence
of barium oxide or aluminium oxide will completely inhibit the
nanostructuring of materials. Hence, in contrast to previous work,
the materials used in this invention have an essentially zero BaO
and Al.sub.2O.sub.3 content.
[0068] Moreover, materials according to this invention have an
essentially zero Li.sub.2O content.
[0069] The addition of alkaline oxide (Oxy.sub.2) is particularly
useful if we wish to reduce the size of segregated domains
(nanodomains of the glass under this invention). However, the
amount introduced must be less than 7% molar (c is less than or
equal to 7) in order to prevent loss of nanostructuring.
[0070] In one particular embodiment, k lies within the range
between 1 and 7, and preferably between 1 and 5.
[0071] In another embodiment, a lies within the range between 1 and
50 (preferably between 1 and 25); b lies within the range 1 and 35,
more preferably between 1 and 25, and most preferably between 2 and
25, while k lies within the range between 1 and 7, and preferably
between 1 and 5.
[0072] In one particular embodiment, the material of the invention
comprises 100% weight of a composition of formula I as defined
above.
[0073] In an embodiment, the material of this invention comprises
in addition to the composition of formula (I), other additives in
normal use in glass-making and/or optic methods. These standard
additives are well known to those skilled in the art.
[0074] For the purposes of this invention, "in addition" means a
quantity of additive elements sufficient to attain 100% per unit
weight for the material in question. Accordingly, the material of
this invention may include up to 3% (from 0% to 3%), or up to 1%
(from 0% to 1%) by weight of standard additive elements, in
relation to the overall weight of that material.
[0075] By way of example, we might cite normal additives such as
carbon or sodium sulphate, which are used to enhance refining on an
industrial scale.
[0076] Dopants are typically used to create variation in the
optical properties of glasses and vitro-ceramics. For example, it
is known that doping with elements belonging to the group of rare
transition elements or earths makes it possible to select the
spectral emission range. The dopant element, its concentration and
degree of oxidisation, are selected according to the composition of
the host matrix and optical properties being sought for that
material. Dopants can be selected from among transition elements
(for example, Cr, Mn, Fe, Co, Ni, Ti, W, etc.). They may also be
selected from among rare earths, preferably the lanthanides. Better
still, dopants may be selected from among scandium, yttrium,
lanthane, cerium, praseodymium, neodymium, samarium, europium,
gadolinium, terbium, dysprosium, holmium, erbium, thulium,
ytterbium, lutecium and mixtures thereof. Europium, cerium, erbium,
nickel and manganese are to be preferred, while those skilled in
the art may see fit to produce a co-dopant, using multiple rare
earths and/or transition elements, depending on the desired optical
properties.
[0077] When these are present, dopants may form up to 3% per unit
mass, but preferably up to 1% per unit mass, of the overall
composition of the material. Thus, the material will typically
include less than 3% by weight, or less than 1% by weight, of
dopants.
[0078] Materials of this invention are transparent, or at very
least translucent. This property is essential to permit of the use
of materials of this invention in optics. Refractory materials,
cements, mortars, that might otherwise be prepared using the same
raw materials as materials of this invention, are not transparent.
Moreover, those materials are not obtained using a glass-making
procedure.
[0079] The vitroceramics of this invention are distinguished from
materials that are obtained through sintering by their density: the
density of vitroceramics under this invention is in essence their
theoretical density (lack of porosity). By theoretical density, we
mean density as calculated using crystallographic data (mesh
structure and parameters) in the absence of porosity. The use of a
glass-making procedure enables us to obtain a material with
essentially the theoretical density, which is to say we find as
absence of porosity. On the other hand, materials obtained by
sintering (including pressing) require complex and expensive
treatments in order to reduce any residual porosity that would
compromise transparency. For the purposes of this invention, by
"absence of porosity", we mean the material's porosity is less than
0.5%. Once porosity becomes too great, (typically greater than
0.5%), the material will lose its transparency.
[0080] Thus, the preparation of vitroceramics and glasses according
to this invention, using a glass-making procedure combined with the
choice of compositions of formula (I), imparts some remarkable
properties to the materials used: the high degree of transparency
intrinsic to the process (lack of porosity) and the compositions of
materials, readily adjustable optical properties according to the
composition chosen, the size of nanostructured domains and the
presence and choice of dopants, the ability to obtain a variety of
shapes and important dimensions by virtue of the process (pouring
into a mould), and lastly much lower costs than optical materials
of comparable compositions, thanks to an inexpensive process.
[0081] Methods of Producing Specific Glasses and Vitroceramics.
[0082] Germanates
[0083] In one particular embodiment, y is equal to 0. To simplify,
compositions under this method of production are recited as
germanates.
[0084] Advantageously, x therefore lies within the range between 50
and 98, and preferably between 60 and 98.
[0085] Preferably, in this embodiment, z is equal to 0.
[0086] Advantageously, a lies within the range between 0.75 and 15,
and preferably between 1 and 15.
[0087] In one particular embodiment, k lies within the range
between 1 and 3. In another specific embodiment, k is equal to
0.
[0088] For example, glasses and vitroceramics were obtained showing
a composition selected from among these formula compositions:
[0089] 98GeO.sub.2-0.75Ga.sub.2O.sub.3-1.25ZnO.
[0090]
78.04GeO.sub.2-9.76ZnO-9.76Ga.sub.2O.sub.3-2.44Na.sub.2O.
[0091] 60 GeO.sub.2-3Na.sub.2O-13.9Ga.sub.2O.sub.3-23.1ZnO.
[0092] 90GeO.sub.2-3.75Ga.sub.2O.sub.3-6.25AgO.
[0093] 84GeO.sub.2-6GA.sub.2O.sub.3-10ZnO.
[0094] 60GeO.sub.2-3Na.sub.2O-13.9Ga.sub.2O.sub.3-23.1MgO.
[0095] 92GeO.sub.2-2Ga.sub.2O.sub.3.-6Bi.sub.2O.sub.3.
[0096] 87 GeO.sub.2-1K.sub.2O-3Ga.sub.2O.sub.3-9WO.sub.3.
[0097] 90GeO.sub.2-3.75Ga.sub.2O.sub.3-6.25ZnO.
[0098] 90GeO.sub.2-3.75Ga.sub.2O.sub.3-6.25Bi.sub.2O.sub.3. and
[0099] 88GeO.sub.2-5.4Ga.sub.2O.sub.3-6.6AgO.
[0100] Silicates
[0101] In one particular embodiment, x is equal to 0. To simplify,
compositions under this method of production are recited as
silicates.
[0102] Advantageously, y therefore lies within the range between 40
and 60, preferably between 43 and 55.
[0103] In addition, advantageously, z lies within the range between
0 and 10, is preferably equal to 0.
[0104] Advantageously, a lies within the range between 10 and 30,
preferably between 20 and 25.
[0105] Preferably b should lie within the range between 10 and 35,
most preferably between 14 and 25.
[0106] Advantageously, k lies within the range between 3 and 6.
[0107] Glasses and vitroceramics were obtained showing a
composition selected from among these formula compositions:
[0108] 55SiO.sub.2-5Na.sub.2O-23Ga.sub.2O.sub.3-17ZnO,
[0109] 44SiO.sub.2-6Na.sub.2O-25Ga.sub.2O.sub.3-25MgO,
[0110]
60SiO.sub.2-5Na.sub.2O-1K.sub.2O-20Ga.sub.2O.sub.3-10ZnO-4Nb.sub.2O-
.sub.5, and
[0111] 55SiO.sub.2-5Na.sub.2O-20Ga.sub.2O.sub.3-20ZnO.
[0112] Silicogermanates
[0113] In this specific embodiment, x and y are both other than 0.
To simplify, compositions under this method of production are
recited as silicogermanates.
[0114] Advantageously, x and y are each independently within the
range between 10 and 80, and preferably between 30 and 70.
[0115] Preferably, in this embodiment, x and y are such that x+y
should preferably be between 50 and 95, more preferably between 60
and 98, and most preferably between 80 and 95.
[0116] In addition, advantageously, z lies within the range between
0 and 10. In one particular embodiment, z is equal to 0. In another
particular embodiment, z is equal to 10.
[0117] Advantageously, a lies within the range between 0.1 and 10,
most preferably between 1 and 5.
[0118] Preferably, b should be between 1 and 5, most preferably
between 4 and 5.
[0119] In one particular embodiment, k lies within the range
between 1 and 3. In another particular embodiment, k is equal to
0.
[0120] Specifically, glasses and vitroceramics were obtained
showing a composition selected from among these formula
compositions:
[0121] 42GeO.sub.2-50SiO.sub.2-3Ga.sub.2O.sub.3-5ZnO,
[0122]
70GeO.sub.2-10SiO.sub.2-2Na.sub.2O-4Ga.sub.2O.sub.3-4Bi.sub.2O.sub.-
3, and
[0123]
50GeO.sub.2-30SiO.sub.2-10B.sub.2O.sub.3-5Ga.sub.2O.sub.3-5ZnO.
[0124] Method of Production for Glasses and Vitroceramics According
to the Invention:
[0125] This invention also concerns a manufacturing process of a
transparent glass according to the invention.
[0126] The glass is prepared through fusion of raw materials
(initial oxides, or their precursors if applicable) going into its
composition to produce a liquid, followed by solidification of that
liquid by cooling. Segregation of the glass takes place at the step
of liquid formation or cooling. These steps therefore allow the
introduction of nanostructuring.
[0127] The manufacturing process of a nanostructured glass under
this invention comprises the successive steps:
[0128] 1--melting of initial oxides, or if applicable their
precursors, present in powder form, at a temperature within the
range between 900.degree. C. and 1700'C,
[0129] 2--cooling,
[0130] resulting in a transparent or translucent nanostructured
glass containing at least 97%, i.e. 97% to 100%, preferably 99% to
100% by weight, in relation to the overall weight of the glass, of
a composition of the following formula I:
(GeO.sub.2).sub.x(SiO.sub.2).sub.y(B.sub.2O.sub.3).sub.z(Ga.sub.2O.sub.3-
).sub.a(Oxy.sub.1).sub.b(Oxy.sub.2).sub.k (I)
[0131] where:
[0132] Oxy.sub.1 is an oxide selected from among ZnO, MbO,
NbO.sub.2.5, WO.sub.3, NiO, SnO, TiO.sub.2, BiO.sub.1.5, AgO, CaO,
MnO or a mixture thereof, more preferably selected from among ZnO,
MgO, NbO.sub.2.5, WO.sub.3, NiO, SnO, AgO, CaO, MnO or a mixture
thereof, or even more preferably selected from among ZnO, MgO, AgO,
BiO.sub.1.5, NbO.sub.2.5 or a mixture thereof, but most preferably
of all selected from ZnO, MgO, AgO, NbO.sub.2.5 or a mixture
thereof, and.
[0133] Oxy.sub.2 is an oxide, selected from among Na.sub.2O,
K.sub.2O or a mixture thereof. Oxy.sub.2 is preferably Na.sub.2O,
and
[0134] x is within the range between 0 and 98, and
[0135] y is within the range between 0 and 60, and
[0136] x and y are not simultaneously zero, and
[0137] z is within the range between 0 and 20, preferably between 0
and 10,
[0138] x+y+z+ is within the range between 40 and 98,
[0139] a is within the range between 0.1 and 50, preferably between
0.5 and 25, and
[0140] b is within the range between 0 and 35, preferably between 1
and 35, and
[0141] k is within the range between 0 and 7, preferably between 0
and 5, and
[0142] x, y, z, a, b and k are such that x+y+z++a+b+k=100.
[0143] Therefore, the glass is obtained by melting of initial oxide
powders or their precursors, at a temperature within the range
900.degree. C. and 1700.degree. C. It should be noted that the
temperatures for developing glasses decrease with increasing
germanium oxide content (melting temperature around 1000.degree. C.
for x=90, for example).
[0144] The initial oxides and any precursors are in the form of
normal commercially-available powders (i.e. non-nanometric).
Precursors of oxides may be in a form that makes it possible to
obtain the initial oxide by thermal treatment, for example in the
form of carbonates. For example, a precursor of Na.sub.2O might be
Na.sub.2CO.sub.3, while K.sub.2CO.sub.3 can be used as a precursor
of K.sub.2O.
[0145] Thus, materials under this invention should preferably not
contain fluorides, oxyfluorides, nor sulphides-only oxides.
[0146] Heating may take place in a conventional oven, heated for
example by gas and/or fitted with heating resistors. The melt
mixture is then cooled, and if need be poured into a mould.
[0147] This process may also include an additional annealing step
aiming to release any tension that may be present in the glass.
[0148] The glasses according to the invention undergo a
segregation, leading to a separation phase, of the
nucleation/growth or spinel type, depending on the composition,
obtained directly in the glass during synthesis, and in particular
at the cooling step. The different nanostructured domains obtained
are homogenous in both composition and size, and maintain a uniform
distribution inside the vitreous matrix. The size of the various
domains thus obtained is adjustable according to composition, and
to a lesser extent according to the rate of cooling of the glass,
but it will remain nanometric.
[0149] It is the nanometric size of this structuring that imparts
transparency to both the glasses and vitroceramics under the
invention. Light diffusion within a nanostructured glass or
vitroceramic is negligible, providing the relationship between the
incident wavelength and size of domains is at least equal to 4. For
example, nanocrystals of a size less than 100 nm ensure
transparency in the visible (i.e. wavelength greater than 400 nm),
and at a higher level in the infra-red.
[0150] Thus, glasses under the invention can be obtained by:
[0151] 1--melting of the initial oxides, or if applicable their
precursors, present in powder form, at a temperature within the
range 900.degree. C. to 1700.degree. C.; and
[0152] 2--cooling.
[0153] This invention also concerns a manufacturing process of a
transparent or translucent nanostructured vitroceramic. This
process comprises a step of manufacturing a transparent glass as
described above, followed by a step of thermal crystallisation
treatment of the glass. The glass production stage comprises a step
of melting of the initial oxides, or if applicable their
precursors, present in powder form, followed by solidification of
the mixture cast during cooling. Thermal crystallisation treatment
makes it possible to crystallise the nanodomains of that glass, and
to convert them into nanocrystals.
[0154] The manufacturing process of a vitroceramic according to the
invention comprises the successive steps of:
[0155] 1--Manufacturing a transparent or translucent nanostructured
glass according to the invention, following the
previously-described process.
[0156] 2--Thermal crystallisation treatment of that glass at a
temperature within the range between 400.degree. C. and 800.degree.
C., and more preferably between 600.degree. C. and 800.degree. C.,
for a period within the range between 15 minutes and 48 hours, more
preferably between 15 minutes and 6 hours, most preferably between
30 minutes and 2 hours.
[0157] The composition of glasses and vitroceramics may be as
previously described for this invention.
[0158] It should be noted that the manufacture of vitroceramics
under this invention should preferably not involve nucleation stage
during the crystallisation treatment. It therefore requires neither
thermal crystallisation treatment in two steps, nor the use of
nucleation agents. Nucleation catalysts are generally added to the
material, even if it already includes an oxide of this type in its
composition. The catalyst plays indeed a specific role, different
from that of oxides in the composition of the material under this
invention.
[0159] The manufacturing process of vitroceramics under this
invention is therefore both simpler and less expensive than the
process described in U.S. Pat. No. 5,786,287.
[0160] Moreover, transparent vitroceramics prepared according to
the process under this invention can readily be moulded into shape.
The glass-making procedure used for their manufacturing process
generally allows of producing parts in highly variable shapes, and
of substantial dimensions, by pouring into a mould. It is not
possible to obtain such a variety of shapes through the techniques
for producing monocrystals or transparent polycrystalline ceramics
produced by ultra-dense nanometric precursors for optical
appliances (obtained by sintering at high pressure and high
temperature). The shape of monocrystals is constrained by the
synthesis process (i.e. a bar). In the case of transparent
polycrystalline ceramics produced from nanometric precursors, the
sintering process used requires a pressing stage (at high
pressure), which is incompatible with obtaining a variety of shapes
(since the traditional shapes obtained under a press are of the
cylindrical or cuboid type).
[0161] Those skilled in the art will know how to adjust the period
of thermal crystallisation treatment so as to obtain transparent or
translucent vitroceramics.
[0162] The oven used for the stage of thermal crystallisation
treatment is preferably a conventional convection oven, and/or
fitted with heating resistors.
[0163] Thus, vitroceramics under this invention are obtainable
through thermal crystallisation treatment of a glass according to
invention, at a temperature within the range between 400.degree. C.
and 900.degree. C., and preferably between 600.degree. C. and
800.degree. C., for a period within the range between 15 minutes
and 48 hours, more preferably between 15 minutes and 6 hours, or
between 30 minutes and 2 hours. Preferably, this process will not
comprise a nucleation step.
[0164] It should be noted that the size of the crystals obtained in
the vitroceramic is correlated with the size of the nanodomains
(i.e. domains of nanometric size) of the equivalent glass, to a
point where the nanocrystals correspond almost perfectly with the
vitreous nanodomains. Thus, thermal crystallisation treatment will
have very little effect on the nanostructure of the material, and
the vitreous matrix will not crystallise noticeably.
[0165] Without wishing to be constrained by the interpretation that
follows, it has been noted in experiments that the composition of
the glass according to the invention, particularly as a function of
the parameters x, y and k of the composition formula (I) as
previously defined, make it possible to have an effect on the size
of nanodomains. The greater the value of x, and/or y, and/or k are,
the more the size of the nanodomain will decrease.
[0166] Moreover, the rate of cooling of the glass also affects the
size of the nanodomains of the glass to a lesser extent: the more
the cooling speed is increased, the smaller the nanodomains
(domains of nanometric size) will be.
[0167] In this way it is possible to control optic properties, and
specifically the transparency, of materials under this invention,
particularly as a function of parameters x, y and k of the
composition of formula (I), as previously defined.
[0168] Use of Vitroceramics and Glasses According to the
Invention.
[0169] Ultimately, this invention concerns the use of a
vitroceramic or glass under the invention to manufacture materials
for optical purposes, particularly of massive types (for example
lenses or filters), powders, fibres (for example optic fibre or
laser fibre) or layers.
[0170] Glasses and vitroceramics produced under this invention have
the properties of transparency in both the visible and infra-red
domains, thereby opening up the way to many optical applications
(photonic and telecommunications equipment, random laser beams,
etc.), especially when glasses and vitroceramics according to this
invention include dopants.
[0171] In particular, scintillator materials have applications in
the field of medical imaging, and in the field of high-energy
physics. There are also applications requiring less high
performance in the domain of detection (for example, in geology).
Luminescent (fluorescent or phosphorescent) materials find
applications in the fields of lighting and displays; for example,
they can be used in LEDs (light-emitting diodes).
[0172] Specifically, vitroceramics whose y is equal to 0 (i.e.
germanates) show excellent optical performance, especially in the
infra-red. In particular, they show transparent properties at
wavelengths within the range between 400 nm and 8 .mu.m. They are
therefore eminently well suited for use as a laser or scintillator
material, especially when they include dopants, for example Ce, Eu,
Pr, Nd, Tm, Dy, Er, Yb, Ho, Ti, Cr, Ni, Bi or mixtures thereof.
[0173] As far as vitroceramics whose x is equal to 0 (i.e.
silicates) are concerned, these are less expensive, but are
transparent only in the visible and near infra-red domain (i.e.
wavelength within the range between 400 nm and 3 .mu.m). They are
therefore eminently well suited to use as a material for frequency
conversions, particularly in the field of lighting, laser beams or
scintillators. In the case of use as a scintillator or laser
material, vitroceramics under this invention include dopants,
including Ce, Eu, Pr, Nd, Yb, Ho, Ti, Cr, Ni or Bi or mixtures
thereof.
[0174] It should be noted that vitroceramics under this invention
have optical and physical properties superior to those of the
equivalent glasses.
[0175] However, some applications do not call for very high ray
resolution, but rather a sufficiently powerful intensity of light.
This applies particularly to lighting and displays. Glasses are
therefore eminently well suited here.
[0176] Thus, depending on the embodiment, glasses and vitroceramics
according to the invention may be used to manufacture material for
lighting or for displays.
[0177] Conversely, in the case of vitroceramics, diffusion can be
controlled in order to use the phenomena of diffusion and emission
of the material to good effect, making it possible for example to
obtain an amplification phenomenon of the random laser-beam type.
Vitroceramics under the invention are used to produce random
laser-beams.
[0178] According to an embodiment, vitroceramics according to the
invention are used to manufacture medical material, preferably for
medical imaging. An example of such a use was described by Chermont
et al, Proc. Natl. Acad. Sci. U.S.A. 2007, 104 (22), 9266-9271.
[0179] A specific case concerns the use of a glass according to the
invention for laser inscription. A laser scan (run precisely by a
control program) can induce an intermittent crystallisation (under
the impact of radiation and localised heating produced by the
laser). This technique facilitates marking of the glass by contrast
between the glass and the vitroceramic points, and a change in its
luminescence properties.
DESCRIPTIONS OF THE FIGURES
[0180] FIG. 1: Transmittance curves (as %, y-coordinate) according
to wavelength (as nm, x-coordinate) of glasses (solid line) and
vitroceramics (stippled line) of (a) germanate
(78GeO.sub.2-9.8ZnO-9.8GaO.sub.3-2.4Na.sub.2O), and (b) silicate
(55SiO.sub.2-5Na.sub.2O-23Ga.sub.2O.sub.3-17ZnO). Photographs of
transparent nanostructured glasses (On the left) and vitroceramics
(at right), developed according to the invention, are also
shown.
[0181] FIG. 2: Negatives of electronic microscopy in transmission
(MET) of a glass and vitroceramic of the composition:
84GeO.sub.2-6Ga.sub.2O.sub.3-10ZnO (segregation of the
nucleation/growth type). On the left, negative of nanostructured
glass; at right, negative of the equivalent vitroceramic, obtained
through thermal crystallisation treatment. The negatives of
associated electronic diffraction are shown as an inset.
[0182] FIG. 3: Negative of electronic microscopy in transmission
(MET) of a nanostructured glass (separation of the spinel phase) of
the composition 80GeO.sub.2-7.5Ga.sub.2O.sub.3-12.5ZnO.
[0183] FIG. 4: Negatives of electronic microscopy in transmission
(MET) of a glass and a vitroceramic of the composition:
55SiO.sub.2-5Na.sub.2O-20Ga.sub.2O.sub.3-20AnO. On the left,
negative of the nanostructured glass (separation of the spinel
phase); at right, negative of equivalent vitroceramic, obtained
through thermal crystallisation treatment of the glass.
[0184] FIG. 5: Negatives of electronic microscopy in transmission
(MET) of a glass and of a vitroceramic of the composition:
90GeO.sub.2-3.75Ga.sub.2O.sub.3-6.25Bi.sub.2O.sub.3. On the left,
negative of the nanostructured glass (separation of
nucleation-growth phase with nanostructuring of very small size, in
the order of a few nm); at right, negative of the equivalent
vitroceramic, obtained through thermal crystallisation treatment of
the glass.
[0185] FIG. 6: Spectrum of photoluminscence in the infra-red
(.lamda..sub.excitation=980 nm) of a nanostructured vitroceramic of
the composition: 88GeO.sub.2-5.4Ga.sub.2O.sub.3-6.6ZnO, doped with
nickel (Ni.sup.2+, 0.05 by weight). The x-coordinate axis depicts
wavelengths in nm, while the y-coordinate axis depicts intensity,
expressed as an arbitrary unit.
[0186] FIG. 7: Spectrum of conversion photoluminscence at a
wavelength that is shorter than that of the emission
("up-conversion"), for .lamda..sub.excitation=980 nm of a
nanostructured glass of the composition
88GeO.sub.2-5.4Ga.sub.2O.sub.3-6.6ZnO, doped with 0.5 per unit mass
of erbium (Er.sup.3+). The x-coordinate axis depicts wavelengths in
nm, while the y-coordinate axis depicts intensity, expressed as an
arbitrary unit.
[0187] FIG. 8: Spectrum of excitation (On the left) and emission
spectrum (at right) of a vitroceramic and a glass of nanostructured
germanate of composition 90GeO.sub.2-6.25ZnO-3.75Ga.sub.2O.sub.3,
doped with terbium (Tb.sup.3+/Tb.sup.4+, 0.25 by weight). The
x-coordinate axis depicts wavelengths in nm, while the y-coordinate
axis depicts intensity, expressed as an arbitrary unit. In the case
of the glass, the excitation spectrum corresponds to the emission
as measured at 542 nm, while the emission spectrum corresponds to
excitation at a wavelength of 260 nm. In the case of the
vitroceramic, the excitation spectrum corresponds to the emission
as measured at 450 nm, while the emission spectrum corresponds to
excitation at a wavelength of 286 nm. The excitation curve of the
glass (solid line) shows a maximum for around .lamda.=240 nm,
whereas the excitation curve for the vitroceramic (stippled line)
shows a maximum for around .lamda.=280 nm. The emission curve for
the glass (solid line) shows four slight peaks, with an intense
peak at around 550 nm. The vitroceramic's emission curve (stippled
line) shows a broad peak, including a gentle "shoulder" towards 550
nm.
[0188] FIG. 9: Spectrum of excitation (On the left) and spectrum of
emission (at right) of a nanostructured silicate vitroceramic and
glass with the identical composition, doped with manganese.
(Mn.sup.2+, 0.1 by weight). The x-coordinate axis depicts
wavelengths in nm, while the y-coordinate axis depicts intensity,
expressed as an arbitrary unit. In the case of the glass, the
excitation spectrum corresponds to the emission as measured at 619
nm, while the emission spectrum corresponds to excitation at a
wavelength of 272 nm. In the case of the vitroceramic, the
excitation spectrum corresponds to the emission as measured at 645
nm, while the emission spectrum corresponds to excitation at a
wavelength of 272 nm. The excitation curve for the glass (solid
line) shows a maximum for around .lamda.=275 nm with high
intensity, whereas the excitation for the vitroceramic (stippled
line) shows a maximum for around .lamda.=270 nm, with a lower
intensity than that of the glass. The emission curve of the glass
(solid line) shows broad peaks, with a maximum intensity at around
.lamda.=625 nm, which is below that of the vitroceramic (the signal
of the glass is less intense than that of the vitroceramic). The
vitroceramic's emission curve (stippled line) also shows broad
peaks, with a maximum intensity for around .lamda.=530 nm.
EXAMPLES
[0189] The following examples are intended to illustrate the
invention in greater detail, but are by no means exhaustive. In
particular, the methods to be described below are the laboratory
procedures, which can readily be adapted to an industrial scale by
those skilled in the art.
[0190] Powders of oxide precursors are first weighed out in the
desired proportions, and then ground and mixed into a mortar. Where
carbonates are used, a decarbonisation step is carried out. The
glasses and vitroceramics are then synthesised from the mixtures
prepared as already described, by melting in a conventional oven
(fitted with heating resistors) at a temperature within the range
between 900.degree. C. and 1700.degree. C., followed by cooling of
the liquid. Temperatures of vitreous production decrease with the
increase in germanium oxide content. In the case of vitroceramics,
a thermal crystallisation treatment is then carried out in a
conventional laboratory oven at a temperature within the range
between 400.degree. C. and 900.degree. C.
[0191] Example of Laboratory Production of a Glass and its
Equivalent Vitroceramic, Adapted for Implementation on an
Industrial Scale.
[0192] Glass Production Method
[0193] In order to prepare 2 g glass of the molar composition
78.04GeO.sub.2-9.76ZnO-9.76Ga.sub.2O.sub.3-2.44Na.sub.2O, the
following weighing operations are carried out:
[0194] 1.4927 g GeO.sub.2
[0195] 0.1452 g ZnO
[0196] 0.3344 g Ga.sub.2O.sub.3
[0197] 0.0493 g Na.sub.2CO.sub.3.
[0198] After weighing out individually, the complete set of
precursors is ground and mixed thoroughly into an agate mortar. The
mixture is then placed in a platinum crucible.
[0199] In view of the presence of sodium carbonate, the mixture
then undergoes decarbonisation treatment (gradual heating
(10.degree. C./min.) to 900.degree. C. and held at that temperature
for 6 hours, then chilled in the oven, (which has been shut down)
in order to eliminate the CO.sub.2 present in the sodium carbonate,
thereby making it possible to obtain the sodium oxide of the
composition.
[0200] After the decarbonisation treatment (which is applied only
where there is carbonate in the mixture of precursors), the
platinum crucible is placed in a hot muffle furnace at 1300.degree.
C. and heated for 30 minutes. On completion of heating, the mixture
cast is removed from the oven and chilled in the crucible (chilled
atmospherically).
[0201] In this way we obtain a glass according to the invention, of
the formula
78.04GeO.sub.2-9.76ZnO-9.76Ga.sub.2O.sub.3-2.44Na.sub.2O.
[0202] Method of Vitroceramic Production
[0203] The glass, synthesised as already shown, then undergoes
thermal crystallisation treatment in a tubular oven (for 3 hours at
615.degree. C.), which will produce a transparent nanostructured
vitroceramic.
[0204] Implementation on an Industrial Scale
[0205] In the case of an industrial method, some steps can be
amended to take account of energy-consumption considerations. For
example, the decarbonisation phase could be merged directly into
the heating phase (one step). Conventional refining additives,
familiar in the field, may be also be added to facilitate fusion of
the glass and the elimination of bubbles. On the other hand, the
annealing of crystallisation could be done while cooling the glass,
for example directly in a mould containing the ground glass (mould
kept for 3 hours in an oven at 615.degree. C.).
[0206] Transmission of glasses and vitroceramics was measured in
the 250 nm-8000 nm spectral domain, using a dual-beam
spectrophotometer.
[0207] Glasses and vitroceramics were synthesised using a similar
method, corresponding to the compositions of formula (I):
(GeO.sub.2).sub.x(SiO.sub.2).sub.y(B.sub.2O.sub.3).sub.z(Ga.sub.2O.sub.3-
).sub.a(Oxy.sub.1).sub.b(Oxy.sub.2).sub.k (I),
[0208] in which:
TABLE-US-00001 Germanate b k x y z A (Oxy 1) (Oxy2)
98GeO.sub.2--0.75Ga.sub.aO.sub.3--1.25ZnO 98 0 0 0.75 1.25 0 (ZnO)
60GeO.sub.2--3Na.sub.2O--13.9Ga.sub.2O.sub.3--23.1ZnO 60 0 0 13.9
23.1 3 (ZnO) (Na.sub.2O) 90GeO.sub.2--3.75Ga.sub.2O.sub.3--6.25AgO
90 0 0 3.75 6.25 0 (AgO) 84GeO.sub.2--6Ga.sub.2O.sub.3--10ZnO 84 0
0 6 10 0 (ZnO)
60GeO.sub.2--3Na.sub.2O--13.9Ga.sub.2O.sub.3--23.1MgO 60 0 0 13.9
23.1 3 (MgO) (Na.sub.2O)
92GeO.sub.2--2Ga.sub.2O.sub.3--6Bi.sub.2O.sub.3 86.8 0 0 1.9 11.3 0
(BiO.sub.1.5) 87GeO.sub.2--1K.sub.2O--3Ga.sub.2O.sub.3--9WO.sub.3
87 0 0 3 9 1 (WO.sub.3) (K.sub.2O)
90GeO.sub.2--3.75Ga.sub.2O.sub.3--6.25ZnO 90 0 0 3.75 6.25 0 (ZnO)
90GeO.sub.2--3.75Ga.sub.2O.sub.3--6.25Bi.sub.2O.sub.3 84.7 0 0 3.5
11.8 0 (BiO.sub.1.5) 88GeO.sub.2--5.4Ga.sub.2O.sub.3--6.6ZnO 88 0 0
5.4 6.6 0 (ZnO)
78.04GeO.sub.2--9.76ZnO--9.76Ga.sub.2O.sub.3--2.44Na.sub.2O 78.04 0
0 9.76 9.76 2.44 (ZnO) Na.sub.2O b k x y z a (Oxy.sub.1)
(Oxy.sub.2) Silicate
55SiO.sub.2--5Na.sub.2O--23Ga.sub.2O.sub.3--17ZnO 0 55 0 23 17 5
(ZnO) (Na.sub.2O) 44SiO.sub.2--6Na.sub.2O--25Ga.sub.2O.sub.3--25
MgO 0 44 0 25 25 6 (MgO) (Na.sub.2O)
60SiO.sub.2--5Na.sub.2O--1K.sub.2O--20Ga.sub.2O.sub.3--10ZnO--4Nb.sub.2O.s-
ub.5 0 57.8 0 19.2 17.3 5.7 (7.7 (4.8 NbO.sub.2.5, Na.sub.2O, 9.6
0.9K.sub.2O) (ZnO)
55SiO.sub.2--5Na.sub.2O--20Ga.sub.2O.sub.3--20ZnO 0 55 0 20 20 0
(ZnO) Silicogermanate
42GeO.sub.2--50SiO.sub.2--3Ga.sub.2O.sub.3--5ZnO 42 50 0 3 5 0
(ZnO)
70GeO.sub.2--10SiO.sub.2--2Na.sub.2O--4Ga.sub.2O.sub.3--4Bi.sub.2O.sub.3
67.4 9.6 0 3.8 7.7 1.9 (BiO.sub.1.5) (Na.sub.2O)
50GeO.sub.2--30SiO.sub.2--10B.sub.2O.sub.3--5Ga.sub.2O.sub.3--5ZnO
50 30 10 5 5 0 (ZnO)
[0209] Summary table of synthesised compositions.
[0210] Where appropriate, dopants were added to these compositions.
Dopants were added during the manufacturing process for doped
glasses and vitroceramics in powder form, then ground and mixed
with other powders of precursors, as described above in the example
of glass synthesis of the formula
78.04GeO.sub.2-9.76ZnO-9.76Ga.sub.2O.sub.3-2.44Na.sub.2O.
[0211] Photographs of glasses and vitroceramics of (a) germanate
(78GeO.sub.2-9.8ZnO-9.8Ga.sub.2O.sub.3-2.4Na.sub.2O), and (b)
silicate (55SiO.sub.2-5Na.sub.2O-23Ga.sub.2O.sub.3-17ZnO) are shown
in FIG. 1. These illustrate the transparency of the materials
according to the invention.
[0212] In addition, FIG. 2 shows the negatives of electronic
microscopy in transmission (MET) of a glass and vitroceramic of the
composition: 84GeO.sub.2-6Ga.sub.2O.sub.3-10ZnO. The negative of
glass reveals segregation of the nucleation/growth type, of
nanometric size.
[0213] FIG. 3 shows the negatives of electronic microscopy in
transmission (MET) of a nanostructured glass with spinel-phase
separation, of the composition
80GeO.sub.2-7.5Ga.sub.2O.sub.3-12.5ZnO.
[0214] With regard to FIG. 4, it depicts compositions of a glass
and vitroceramic of the composition:
55SiO.sub.2-5Na.sub.2O-20Ga.sub.2O.sub.3-20ZnO (negatives of
electronic microscopy in transmission (MET). In this instance, the
glass shows spinel-phase separation of nanometric size.
[0215] FIG. 5 shows negatives of electronic microscopy in
transmission (MET) of a nanostructured glass with nucleation-growth
phase separation, with nanostructuring of a very small size in the
order of a few nm, and a vitroceramic of the composition
90GeO.sub.2-3.75Ga.sub.2O.sub.3-6.25Bi.sub.2O.sub.3.
[0216] FIG. 6 describes a spectrum of photoluminescence in the
infra-red (.lamda..sub.excitation=980 nm) of a nanostructured
vitroceramic of the composition:
88GeO.sub.2-5.4Ga.sub.2O.sub.3-6.6ZnO, doped with nickel
(Ni.sup.2+, 0.05% by weight).
[0217] FIGS. 7 to 9 show spectra depicting the optical properties
of glasses and vitroceramics of the composition:
88GeO.sub.2-5.4Ga.sub.2O.sub.3-6.6ZnO, doped with 0.5% per unit
mass of erbium (Er.sup.3+),
90GeO.sub.2-6.25ZnO-3.75Ga.sub.2O.sub.3, doped with terbium
(Tb.sup.3+/Tb.sup.4+, 0.25% by weight), and
90GeO.sub.2-6.25ZnO-3.75Ga.sub.2O.sub.3, doped with manganese
(Mn.sup.2+, 0.1% by weight).
* * * * *